1. Field of the Invention
The present invention relates to a method of and an apparatus for evaluating a diagnosing function to diagnose a transient response of a variable valve mechanism adapted for changing operating characteristics of an engine valve.
2. Description of the Related Art
Japanese Unexamined Patent Publication No. 2000-073794 discloses a technique in which a deviation between a desired value and an actual value of the operating characteristics of the engine valve is calculated, and when a state where the deviation exceeds a determination value continues for a time period which is equal to or more than a predetermined period of time, an occurrence of response delay in the variable valve mechanism is diagnosed.
If the diagnosing processing normally functions, it is possible to alert a driver to the abnormal condition that the response delay is increased. However, if the diagnosis processing does not function normally, the engine is operated in a state where the large response delay is generated, and the performance of the engine at the time of acceleration thereof accompanying switching of desired operating characteristics of the engine is deteriorated.